Hyper-V Windows 2012 r2 Poor network performance

Question

Hi,
Since that I installed Windows 2012 R2 and Hyper-v, I notice that is very slow performing copy operations from the VMs to the physical machine (appears to be lock to 10MB). Firs I though that this issue was only between the VMs and the parent OS, now I realized
that when copying between this Hyper-v physical host and another physical host in the same subnet I also get only 10MB of speed.
How do I unlock this 10MB limit??
The switch and all NICs are GIGABIT capable and before using Windows 2012 r2, using the same hardware boxes I was doing 400MB of transfers between physical hosts and VMs??!!
Thank you.

Answer 1

I had the exact same issue with the same AR8151 NIC on my Alienware, only I'm running Windows 8.1. 
I have a VM with both an external (to the AR8151) and an internal NIC which serves as both a domain controller and router (RRAS) for my other VMs (which only have Internal interfaces).  There is no VMQ setting on the adapter, and I messed around with
the offload/RSS settings, but performance would drop whenever this VM would be running.  (Internet speed test would go from 95Mbps downstream to about 24Mbps.).  When I paused or shut down the VM, performance would return to normal. 
I found the issue to be an errant entry in my route table which I have no idea how it happened.  A second default route was created which used the internal IP of the VM with a lower metric.  Simply deleting the route corrected the performance issue.
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0      10.10.1.200        10.10.2.1     
5
          0.0.0.0          0.0.0.0      192.168.1.1    192.168.1.131     10
        10.10.0.0      255.255.0.0         On-link         10.10.2.1    261
        10.10.0.0      255.255.0.0    192.168.1.200    192.168.1.131     11